Risk of pregnancy complications and adverse birth outcomes after maternal A(H1N1)pdm09 influenza: a Norwegian population-based cohort study

Abstract

BackgroundThe effects of maternal influenza infection on the fetus remain unclear. We studied mild influenza and influenza antibodies in relation to birth weight and risks of pre-eclampsia, preterm birth (PTB), and small for gestational age (SGA) birth among the unvaccinated participants in the Norwegian Influenza Pregnancy Cohort.MethodsPregnant women attending a routine ultrasound were recruited from four hospitals in Norway shortly after the 2009 A(H1N1) pandemic. The present study was restricted to unvaccinated participants who were pregnant during the pandemic. Information on the participants was obtained through questionnaires and linkage with national registries. Maternal blood samples were collected at delivery. Women with laboratory-confirmed A(H1N1)pdm09 influenza, a clinical diagnosis of influenza, or self-reported influenza during the pandemic were classified as having had influenza. A(H1N1)pdm09-specific antibodies in serum were detected with the hemagglutination-inhibition assay. Detection of antibodies was considered an indicator of infection during the pandemic in the unvaccinated participants. Odds ratios were estimated with logistic regression. Quantile regression was used to estimate differences in the distribution of birth weight.ResultsAmong the 1258 women included in this study, there were 37 cases of pre-eclampsia, 41 births were PTB, and 103 births were SGA. 226 women (18.0%) had influenza during the pandemic. The majority of cases did not receive medical care, and only a small proportion (1.3%) of the cases were hospitalized. Thus, the cases consisted primarily of women with mild illness. No significant associations between influenza and risk of pre-eclampsia, PTB, or SGA birth were observed. Detection of A(H1N1)pdm09-specific antibodies was associated with a lower 10th percentile of birth weight, β = − 159 g (95% CI − 309, − 9).ConclusionsMild influenza illness during pregnancy was not associated with increased risk of pre-eclampsia, PTB or SGA birth. However, influenza infection during pregnancy may reduce the birth weight of the smallest children.

Incidence and predictors of adverse pregnancy outcomes with maternal HIV-1 immune reconstitution inflammatory response syndrome among women within reproductive age in selected hospitals, Nairobi, Kenya (A prospective cohort study)

“…31.58] (33). Another similar trend withDetection of A (H1N1) pdm09-speci c antibodies was associated with a lower 10th percentile of birth weight, β = − 159 g (95% CI − 309, − 9), with in uenza infection during pregnancy predicting reduction of only but the birth weight of the smallest children(34…”

Effects of COVID-19 infection during pregnancy and neonatal prognosis: what is the evidence?

“…The fact that most pregnant women were from China imposes a considerable challenge to interpret evidence, considering cultural and epidemiological differences when comparing with pregnant women from other countries and cultures. Even though the studies presented considerable variation in terms of the women's ages, covering virtually the entire fertile period, there is less information in terms of gestational age, with an apparent deficit concerning the first trimester of pregnancy, a time when, in terms of embryonic/fetal development, is considered of greatest vulnerability [25]. See, for instance, the case of infections caused by other viruses (Hepatitis B, Rubella, ZIKA, Varicella) [26] safeguarding phylogenetic differences.…”

“…They tested positive and were hospitalized. Such a fact reinforces the need to follow recommendations provided by the Centers for Disease Control and Prevention (CDC) and the WHO to testing risk groups in contact with those diagnosed with COVID-19 [19,20,21,22,23,24,25,26,27,28,29,30], though this approach may not be feasible in some contexts where there is a shortage of tests.…”

Detection of anti‐NS1 antibodies after pandemic influenza exposure: Evaluation of a serological method for distinguishing H1N1pdm09 infected from vaccinated cases

“…8 The main strength of this study was access to human samples from a well-characterized cohort, combining national registry data, self-reported questionnaire data and HI titre data. 17,21,22 During the pandemic, it was mandatory to report LCI and vaccination to the The "+" and "−" signs reflect the case definitions as follows: Uninfected, unvaccinated controls: "−/−," LCI, unvaccinated cases: "+/−," and Vaccinated cases without ILI: "−/+". misclassification of vaccination status is unlikely, 18 as supported by the corresponding HI titre data.…”

“…The main strength of this study was access to human samples from a well‐characterized cohort, combining national registry data, self‐reported questionnaire data and HI titre data . During the pandemic, it was mandatory to report LCI and vaccination to the national registries in Norway.…”